The Center for Competitive Politics has lodged a formal complaint with the Senate Select Committee on Ethics, urging the committee to investigate nine senators for "improperly interfering with the administrative proceedings of the Internal Revenue Service."

Monday's request more specifically asks the committee to look into whether the senators used the IRS to suppress First Amendment speech rights of "certain nonprofit organizations." They are: Carl Levin, D-Mich., Richard Durbin, D-Ill., Charles Schumer, D-N.Y., Jeanne Shaheen, D-N.H., Tom Udall, D-N.M., Sheldon Whitehouse, D-N.H., Al Franken, D-Minn., Michael Bennet, D-Colo., and Jeff Merkley, D-Ore.

Referencing Watergate, the complaint quoted from one of the articles of impeachment against President Richard Nixon. Specifically, that Nixon "endeavoured to obtain from the Internal Revenue Service, in violation of the constitutional rights of citizens, confidential information contained in income tax returns for purpose[s] not authorized by law, and to cause, in violation of the constitutional rights of citizens, income tax audits or other income tax investigations to be initiated or conducted in a discriminatory manner."

The 26-page complaint claims that "to varying degrees, each of the Senators named in this complaint has engaged in exactly this type of conduct, in violation of Senate rules. This Committee must act to ensure that this course of conduct is not repeated, lest it become an accepted political campaign practice," and that the "seriousness of such behavior cannot be understated."